I upgraded from 4.14 to 4.15 by simply running the installer. Upon reboot when I first try to log in by webaccess I get:
ThinLinc Web Access encountered an error:
document.getElementById(…) is null
addConnectionControlHandlers@https://foo.tailbar.ts.net:10000/app/ui.js:319:18 start@https://foo.tailbar.ts.net:10000/app/ui.js:105:12 prime/<@https://foo.tailbar.ts.net:10000/app/ui.js:49:27
(Hostname slightly obfuscated)
Restarting log in seems to resolv the problem and now it works fine. Browser used: Firefox 116.0.3 (64-bits canonical-002)